The U.S. Sentencing Commission is currently investigating the disproportionate incarceration of Native Americans in the U.S., particularly on reservations.

The Tribal Issues Advisory Group–made up of 22 judges and law-enforcement officials, 11 of which are Natives–will be spearheading this extensive federal review.

“No matter how long I have been sentencing in Indian Country, I find it gut-wrenching when I am asked by a family member of a person I have sentenced why Indians are sentenced to longer sentences than white people who commit the same crime,” wrote Ralph Erickson, head of the committee and chief federal district court judge for North Dakota, in a 2014 letter.

Over the past 5 years, the number of Native Americans incarcerated within the federal prison system has increased by 27%. In South Dakota, Native Americans make up nearly 60% of federal cases, yet they account for a mere 9% of the state population.